[Regulation of cholesterol metabolism with dietary addition of oyster mushrooms (Pleurotus ostreatus) in rats with hypercholesterolemia]. / Regulácia metabolizmu cholesterolu hlivou ústricovitou (Pleurotus ostreatus) v diéte u potkana s hypercholesterolémiou.

BACKGROUND: It is generally accepted that lowering of serum cholesterol levels reduces the risk of atherosclerosis. Identification and characterization of natural substances with hypocholesterolemic activity useful in dietetic prevention or treatment of hypercholesterolemia is still relevant in countries with persistent progression of hypercholesterolemia. Addition of oyster mushroom (Pleurotus ostreatus), an industrially produced wood-rotting fungus, to the diet effectively reduced cholesterol accumulation in serum and liver of rats fed a cholesterol diet. The aim of a series of experiments was to explain the biochemical mechanism of this effect. METHODS AND RESULTS: Male Wistar rats fed a cholesterol (0.3%) diet shortly after weaning for a period of 8-10 weeks were used in the experiments. The addition of 5% of dried oyster mushroom to the diet had following effects: reduction of cholesterol level both in serum (5.12 +/- 0.55 vs. 3.44 +/- 0.16 mmol/l, p < 0.02) and liver (241 +/- 12 vs. 113 +/- 11 mmol/kg, p < 0.001); redistribution of cholesterol in favour of high-density lipoproteins; reduced production of very-low-density lipoproteins (135 +/- 7 vs. 96.5 +/- 5 mumol/h/kg, p < 0.001); reduced cholesterol absorption (61.2 +/- 2 vs. 53 +/- 2%, p < 0.02) and reduced HMG-CoA activity in liver (137 +/- 16 vs. 86 +/- 9 pmol/min/mg proteins, p < 0.02). Simultaneously, an increase in 7 alfa-hydroxylase activity in liver (17 +/- 1 vs. 22 +/- 1 pmol/min/mg proteins. p < 0.02) and bile acid excretion (7 +/- 0.9 vs. 11 +/- 0.5 mg/day/rat, p < 0.02) was observed. (Values shown are means +/- SEM.) CONCLUSIONS: Biochemical mechanism of hypocholesterolemic effect of oyster mushroom on cholesterol-fed rats includes reduced production of cholesterol-rich very-low-density and low-density lipoproteins which principally determine cholesterol levels in serum. This effect is related to decreased absorption and biosynthesis of cholesterol together with increase in cholesterol catabolism and excretion of degradation products-bile acids.

Effect of oyster mushroom (Pleurotus Ostreatus) and its ethanolic extract in diet on absorption and turnover of cholesterol in hypercholesterolemic rat.

The effect of the diet containing 5% of powdered oyster mushroom (Pleurotus ostreatus) or an equivalent amount of mushroom ethanolic extract on cholesterol content in serum and liver, on its distribution in lipoproteins, absorption and turnover was studied in male Wistar rats (initial body weight about 70 g) fed a diet with 0.3% cholesterol. 12 weeks of feeding with whole oyster mushroom or mushroom extract reduced cholesterol level in serum by 52 and 33%, respectively. However, cholesterol content in liver was reduced only by whole oyster mushroom (by 20%). Diminished serum cholesterol level was mediated in 60% by reduction of cholesterol in very-low-density lipoproteins. Both whole oyster mushroom and mushroom extract increased the concentration of cholesterol in high-density lipoproteins. Consuming whole oyster mushroom decreased cholesterol absorption (estimated by dual-isotope plasma ratio method) by nearly 16% while no significant effect of mushroom extract could be demonstrated. Feeding the diet containing whole oyster mushroom or its extract reduced the half-times of decay curve of cholesterol-4-14C by 29 and 35%, respectively and reciprocally increased the fractional catabolic rate of plasma cholesterol.

Mechanism of hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats: reduction of cholesterol absorption and increase of plasma cholesterol removal.

The content of cholesterol in the serum and liver of male Wistar rats fed, for the period of 8 weeks shortly after weaning, a diet containing 0.3% of cholesterol was reduced by 33 and 27% by the addition of 5% of dried oyster mushroom powder. Although the level of serum triacylglycerols was not affected by oyster mushroom, their content in liver of rats on mushroom diet was reduced by 41%. Very-low-density lipoproteins and low-density lipoproteins participated by 55 and 38%, respectively, in the total reduction of serum cholesterol. Cholesterol content in high-density lipoproteins was not significantly affected by oyster mushroom. Cholesterol absorption as determined by dual-isotope plasma ratio method was significantly reduced by 14% with oyster mushroom diet. Similarly, this diet increased by 42% the fractional catabolic rate of cholesterol determined by the analysis of decay curve of [4-14C]cholesterol.

Influence of water and ethanol extracts of the oyster mushroom (Pleurotus ostreatus) on serum and liver lipids of the Syrian hamsters.

Extracts from the dried and ground fungus were prepared with water and with 30%, 60% and 85% ethanol, and thickened in vacuum. The whole fungus and extracts were added to the hyperlipidemic diet in amounts equivalent to 3% of the whole fungus. After 6 weeks the whole fungus, its water as well as 30% and 60% ethanol extracts have significantly reduced the contents of cholesterol (C) and triacylglycerols (TG) in the serum. The C and TG contents of the liver were reduced by 34-48% (in the case of TG insignificantly when applying the water and 60% ethanol extracts). The 85% ethanol extracts reduced the C and TG levels in both serum and liver statistically insignificantly by 18-22%. The reduction of serum C by addition of the whole fungus and its water and 30% ethanol extract was decisively affected by the reduction in the C contents in the very low density fraction of lipoproteins.

The mushroom Pleurotus ostreatus reduces secretion and accelerates the fractional turnover rate of very-low-density lipoproteins in the rat.

In male rats fed a diet containing 1.5% cholesterol and 5% of dried mushroom (Pleurotus ostreatus) a significantly reduced accumulation of cholesterol in serum (by 45%) and the liver (by 15%) was observed at the end of the 12th week of the experiment. The decrease in serum cholesterol level by more than 90% is a consequence of the decreased cholesterol concentration of very-low-density lipoproteins (VLDL) and of low-density lipoproteins. Consumption of P. ostreatus reduces the total VLDL entry into the circulation by 19% and accelerates (by 49%) fractional turnover rate of VLDL.

Effect of mushroom Pleurotus ostreatus and isolated fungal polysaccharide on serum and liver lipids in Syrian hamsters with hyperlipoproteinemia.

In Syrian hamsters, a diet with 44% of the calories being fat and containing 52 mg cholesterol (C)/100 g induced an accumulation of blood plasma and liver C and triacylglycerol (TG). In these animals, we studied the effect of dried whole mushroom (Pleurotus ostreatus, 2% in the diet, 6-mo experiment) and ethanol-insoluble residue and structurally defined fungal polysaccharide, both isolated from the mushroom (in both cases, 4% in the diet, 2-mo experiments) on C and TG concentration in serum and liver. Whole mushroom effectively retarded the increase in C and TG in both serum and liver throughout the experiment. The mushroom also reduced the content of all lipids in lipoproteins with densities of less than 1.006 to less than 1.063 g/ml. Very-low-density lipoproteins played a substantial role in the decrease (65-80%) in serum lipids. As a result, the lipoprotein concentration of the specified density classes was reduced by 45-60%, and the concentration of the serum lipoprotein pool was reduced by 40%. Neither the chemical composition of high-density lipoproteins nor their serum concentration was affected by the mushroom. Ethanol-insoluble mushroom residue did not significantly affect serum lipid levels, but it reduced liver TG content. Fungal polysaccharide lowered the C content in serum and liver.

Cholesterol-lowering effect of the mushroom Pleurotus ostreatus in hereditary hypercholesterolemic rats.

We studied the effect of the edible mushroom Pleurotus ostreatus (4% in diet containing 1% of cholesterol) on serum and liver lipids in female rats with hereditary enhanced sensitivity to alimentary cholesterol. We found that the consumption of the mushroom-containing diet prevented serum cholesterol increase which was manifested at the end of the 4th week of the experiment. At the end of the 7th week of the experiment the cholesterolemia was lowered by almost 40% as compared with control animals kept on the same diet but without the mushroom. The decrease in serum cholesterol levels is a consequence of the decreased cholesterol concentrations of very-low-density lipoproteins and of low-density lipoproteins.

Determination of the molecular weight of alpha-amylase, as the enzyme-inhibitor complex, using thin layer gel filtration on Sephadex.

Thin layer gel filtration on Sephadex was performed as a simple method for recognition of the small molecular weight differences of human alpha-amylases from different sources. Activity was located with dry chromogenic substrate, using a replica technique. Undesirable interaction between the gel matrix and substrate binding sites on the enzyme, which causes an anomalous decrease in the migration rate of the enzyme protein, was suppressed by preincubation of the enzyme with appropriate inhibitor. Gradual masking of substrate binding sites of the enzyme by increasing concentrations of amylase inhibitors resulted in two distinct migration rates for the enzyme in thin layer gel filtration. This suggests the existence of two substrate binding sites in the enzyme molecule. Together with thin layer gel affinity chromatography on a mixture of Sephadex and ConA-Sepharose, the method yielded useful data on the molecular weight of amylase and its glycosylated forms and served as a valuable tool for the differential diagnosis of macroamylasaemia.

Production of beta-glucosidase, exo-beta-1,4-glucanase and endo-beta-1,4-glucanase by selected microscopic fungi.

Production of beta-glucosidase, exo-beta-1,4-glucanase and endo-beta-1,4-glucanase was screened in 58 species of imperfect fungi, mucoral fungi and some ascomycetes. beta-Glucosidase activity was found in all of the tested microorganisms, exo-beta-1,4-glucanase activity in 23, and endo-beta-1,4=glucanase activity in 38 microorganisms. Growth on cellobiose was found in all tested microorganisms, growth on carboxymethylcellulose in in 38 tested strains.

Production of alpha-amylase by microscopic fungi.

The amylolytic activity and especially the production of alpha-amylase (EC 3.2.1.1) and alpha-glucosidase (EC 3.2.1.20) was screened in imperfect fungi, mucoral fungi and some ascomycetes. The character of the polysaccharide system, which is responsible for the utilization of alpha (1 to 4) glucan, was specified with a concomitant screening of growth on soluble starch. The amylolytic activity was found in 29 strains out of the 49 tested.

Cellulase activity of higher fungi.

The method of liquefaction of gel from cross-linked cellulose was used for monitoring the cellulolytic activity of 114 cultures of higher fungi, 47 of which belonged to Pleurotus ostreatus. All cultures of P. ostreatus had a low activity. The highest cellulase activity, manifested by Piptoporus betulinus, was comparable with that of Tricloderma viride QM6a.

Biochemical similarities among strains of Aureobasidium pullulans (de Bary) Arnaud.

Seventy-seven properties of Aureobasidium pullulans including utilization of various carbon sources, decomposition of the lignin-cellulose complex and the respective enzymes were checked in the present communication. According to these properties the group of 43 strains was separated in three parts, out of which two groups were found to belong to varieties A. pullulans var. pullulans and A. pullulans var. melanigenum. The third group formed a marginal part. The two varieties differed in numerous biochemical markers, particularly in the absence of monophenol monooxygenase in the variety A. pullulans var. pullulans.

Mannan-hydrolyzing enzymes of yeasts and yeast-like organism.

The ability to degrade mannan in the yeast Saccharomyces cerevisiae, i.e. the ability to produce an enzyme of the alpha-mannosidase type was tested in 57 representatives of various genera and species of yeasts and yeast-like organisms. Their growth was simultaneously monitored on soluble mannan and on 4-nitrophenyl-alpha-D-mannopyradnoside. The majority of strains produced alpha-mannosidase (EC 3.2.1.24).

[beta-1,3-1,4-Glucanase in sporeforming microorganisms. II. Production of beta-glucan-hydrolases by various Bacillus species (author's transl)]. / beta-1,3-1,4-Glucanase in sporenbildenden Mikroorganismen. II. Bildung von beta-Glucan-Hydrolasen durch verschiedene Bacillus-Arten.

Production of beta-1,3-1,4-glucan hydrolase (licheninase) was studied in 45 strains of Bacillus representing 17 various species using lichenin as substrate. It was found that the enzyme was produced by the strains of B. pumilus, B. subtilis, B. amyloliquefaciens, B. polymyxa, B. macerans, B. laterosporus and one strain of B. circulans. A new screening method based on application of a gel prepared from the cross-linked lichenin as an only source of carbon in the cultivation medium is presented. Using this method and methods using other cross-linked gels as carbon sources in a synthetic liquid medium, production of licheninase, amylase and cellulase by the strains tested is compared.

Production of alpha-amylase by yeasts and yeast-like organisms.

Of a total of 177 strains of yeasts and yeast-like organisms only 8 were capable of producing alpha-amylase; most strains were able to utilize 1,4-alpha-glucans by means of enzymes acting on the non-reducing ends of the outer glucan chains.